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Human impacts on the natural environment during the later part of the Holocene (beginning about 4,000 years ago) complicate investigations into environmental change during that period because the signals produced by human-and climate-induced change are sometimes difficult to separate. For example, in the later Holocene, one indicator of increased aridity due to climate change is an increase in pollen from grasses, as forest vegetation gives way to grassland. Such a change in vegetation could alternatively be attributed to human impact in the form of agricultural development. Examples of such human impact from 4,000 years ago would be small-scale, however, since the broad ecosystem changes brought about by the widespread adoption of agricultural technologies occurred later.
Which of the following best describes the function of the highlighted sentence in the context of the passage as a whole?
According to the passage, which of the following is true regarding environmental changes 4,000 years ago?
The waters east of Cape Hangklip were once the center of a lucrative wild-caught abalone fishery, but illegal fishing in the mid-1990 escalated to such levels that the recreational fishery was closed in 2003. When abalones did not rebound, commercial fishing was also banned. Continue declines in abalone were attributed to poaching, but an invasion by rock lobsters during the early 1990s probably intensified the trend. Rock lobsters prey on sea urchins, and increased rock lobster densities coincided with significant decreases in sea urchins. In that area, urchins feed largely by trapping drift kelp, and in doing so provide juvenile abalone with both protective shelter and nourishment. Without urchins` presence, juvenile abalones are less likely to survive to adulthood.
According to the passage, since the early 1990s, sea urchins in the waters east of Cape Hangklip have
According to the passage, which of the following is a true statement about the feeding behaviors of sea urchins?
Price knew about how to do people favors, sometimes just from kindness, but often out of _____.
Caricature can be revealing as well as amusing, and Ager`s novel is both: Ager`s delineation of class, ethnic, and generational struggle is exaggerated for comical effect, but it _____ nonetheless.
Although the claim that no one knows what dark matter is remains _____, some scientists dispute the parallel assertion that dark matter has not been detected.
Benjamin Franklin`s reputation is so much one of appearing scientific investigation with commonsense empiricism that it is somewhat startling to realize how _____ the great experiment`s mentoring truly was.

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